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<a name="gst-plugins-base-libs-GstFFTF64"></a><div class="titlepage"></div>
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<td valign="top">
<h2><span class="refentrytitle"><a name="gst-plugins-base-libs-GstFFTF64.top_of_page"></a>GstFFTF64</span></h2>
<p>GstFFTF64 — FFT functions for 64 bit float samples</p>
</td>
<td class="gallery_image" valign="top" align="right"></td>
</tr></table></div>
<div class="refsect1">
<a name="gst-plugins-base-libs-GstFFTF64.functions"></a><h2>Functions</h2>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="functions_return">
<col class="functions_name">
</colgroup>
<tbody>
<tr>
<td class="function_type">
<a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="returnvalue">GstFFTF64</span></a> *
</td>
<td class="function_name">
<a class="link" href="gst-plugins-base-libs-GstFFTF64.html#gst-fft-f64-new" title="gst_fft_f64_new ()">gst_fft_f64_new</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="gst-plugins-base-libs-GstFFTF64.html#gst-fft-f64-fft" title="gst_fft_f64_fft ()">gst_fft_f64_fft</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="gst-plugins-base-libs-GstFFTF64.html#gst-fft-f64-inverse-fft" title="gst_fft_f64_inverse_fft ()">gst_fft_f64_inverse_fft</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="gst-plugins-base-libs-GstFFTF64.html#gst-fft-f64-window" title="gst_fft_f64_window ()">gst_fft_f64_window</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="gst-plugins-base-libs-GstFFTF64.html#gst-fft-f64-free" title="gst_fft_f64_free ()">gst_fft_f64_free</a> <span class="c_punctuation">()</span>
</td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect1">
<a name="gst-plugins-base-libs-GstFFTF64.other"></a><h2>Types and Values</h2>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="name">
<col class="description">
</colgroup>
<tbody>
<tr>
<td class="datatype_keyword"> </td>
<td class="function_name"><a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64">GstFFTF64</a></td>
</tr>
<tr>
<td class="datatype_keyword">struct</td>
<td class="function_name"><a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64Complex" title="struct GstFFTF64Complex">GstFFTF64Complex</a></td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect1">
<a name="gst-plugins-base-libs-GstFFTF64.includes"></a><h2>Includes</h2>
<pre class="synopsis">#include &lt;gst/fft/fft.h&gt;
</pre>
</div>
<div class="refsect1">
<a name="gst-plugins-base-libs-GstFFTF64.description"></a><h2>Description</h2>
<p><a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> provides a FFT implementation and related functions for
64 bit float samples. To use this call <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#gst-fft-f64-new" title="gst_fft_f64_new ()"><code class="function">gst_fft_f64_new()</code></a> for
allocating a <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> instance with the appropriate parameters and
then call <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#gst-fft-f64-fft" title="gst_fft_f64_fft ()"><code class="function">gst_fft_f64_fft()</code></a> or <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#gst-fft-f64-inverse-fft" title="gst_fft_f64_inverse_fft ()"><code class="function">gst_fft_f64_inverse_fft()</code></a> to perform the
FFT or inverse FFT on a buffer of samples.</p>
<p>After use free the <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> instance with <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#gst-fft-f64-free" title="gst_fft_f64_free ()"><code class="function">gst_fft_f64_free()</code></a>.</p>
<p>For the best performance use <a class="link" href="gst-plugins-base-libs-GstFFT.html#gst-fft-next-fast-length" title="gst_fft_next_fast_length ()"><code class="function">gst_fft_next_fast_length()</code></a> to get a
number that is entirely a product of 2, 3 and 5 and use this as the
<em class="parameter"><code>len</code></em>
 parameter for <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#gst-fft-f64-new" title="gst_fft_f64_new ()"><code class="function">gst_fft_f64_new()</code></a>.</p>
<p>The <em class="parameter"><code>len</code></em>
 parameter specifies the number of samples in the time domain that
will be processed or generated. The number of samples in the frequency domain
is <em class="parameter"><code>len</code></em>
/2 + 1. To get n samples in the frequency domain use 2*n - 2 as <em class="parameter"><code>len</code></em>
.</p>
<p>Before performing the FFT on time domain data it usually makes sense
to apply a window function to it. For this <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#gst-fft-f64-window" title="gst_fft_f64_window ()"><code class="function">gst_fft_f64_window()</code></a> can comfortably
be used.</p>
<p>Be aware, that you can't simply run <a class="link" href="gst-plugins-base-libs-GstFFTF32.html#gst-fft-f32-inverse-fft" title="gst_fft_f32_inverse_fft ()"><code class="function">gst_fft_f32_inverse_fft()</code></a> on the
resulting frequency data of <a class="link" href="gst-plugins-base-libs-GstFFTF32.html#gst-fft-f32-fft" title="gst_fft_f32_fft ()"><code class="function">gst_fft_f32_fft()</code></a> to get the original data back.
The relation between them is iFFT (FFT (x)) = x * nfft where nfft is the
length of the FFT. This also has to be taken into account when calculation
the magnitude of the frequency data.</p>
</div>
<div class="refsect1">
<a name="gst-plugins-base-libs-GstFFTF64.functions_details"></a><h2>Functions</h2>
<div class="refsect2">
<a name="gst-fft-f64-new"></a><h3>gst_fft_f64_new ()</h3>
<pre class="programlisting"><a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="returnvalue">GstFFTF64</span></a> *
gst_fft_f64_new (<em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gint"><span class="type">gint</span></a> len</code></em>,
                 <em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> inverse</code></em>);</pre>
<p>This returns a new <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> instance with the given parameters. It makes
sense to keep one instance for several calls for speed reasons.</p>
<p><em class="parameter"><code>len</code></em>
 must be even and to get the best performance a product of
2, 3 and 5. To get the next number with this characteristics use
<a class="link" href="gst-plugins-base-libs-GstFFT.html#gst-fft-next-fast-length" title="gst_fft_next_fast_length ()"><code class="function">gst_fft_next_fast_length()</code></a>.</p>
<p><span class="annotation">[<acronym title="Exposed in C code, not necessarily available in other languages."><span class="acronym">skip</span></acronym>]</span></p>
<div class="refsect3">
<a name="gst-fft-f64-new.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>len</p></td>
<td class="parameter_description"><p>Length of the FFT in the time domain</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>inverse</p></td>
<td class="parameter_description"><p><a href="/usr/share/gtk-doc/html/glib/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> if the <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> instance should be used for the inverse FFT</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="gst-fft-f64-new.returns"></a><h4>Returns</h4>
<p> a new <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> instance.</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="gst-fft-f64-fft"></a><h3>gst_fft_f64_fft ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
gst_fft_f64_fft (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> *self</code></em>,
                 <em class="parameter"><code>const <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *timedata</code></em>,
                 <em class="parameter"><code><a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64Complex" title="struct GstFFTF64Complex"><span class="type">GstFFTF64Complex</span></a> *freqdata</code></em>);</pre>
<p>This performs the FFT on <em class="parameter"><code>timedata</code></em>
 and puts the result in <em class="parameter"><code>freqdata</code></em>
.</p>
<p><em class="parameter"><code>timedata</code></em>
 must have as many samples as specified with the <em class="parameter"><code>len</code></em>
 parameter while
allocating the <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> instance with <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#gst-fft-f64-new" title="gst_fft_f64_new ()"><code class="function">gst_fft_f64_new()</code></a>.</p>
<p><em class="parameter"><code>freqdata</code></em>
 must be large enough to hold <em class="parameter"><code>len</code></em>
/2 + 1 <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64Complex" title="struct GstFFTF64Complex"><span class="type">GstFFTF64Complex</span></a> frequency
domain samples.</p>
<div class="refsect3">
<a name="gst-fft-f64-fft.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>self</p></td>
<td class="parameter_description"><p><a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> instance for this call</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>timedata</p></td>
<td class="parameter_description"><p>Buffer of the samples in the time domain</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>freqdata</p></td>
<td class="parameter_description"><p>Target buffer for the samples in the frequency domain</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="gst-fft-f64-inverse-fft"></a><h3>gst_fft_f64_inverse_fft ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
gst_fft_f64_inverse_fft (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> *self</code></em>,
                         <em class="parameter"><code>const <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64Complex" title="struct GstFFTF64Complex"><span class="type">GstFFTF64Complex</span></a> *freqdata</code></em>,
                         <em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *timedata</code></em>);</pre>
<p>This performs the inverse FFT on <em class="parameter"><code>freqdata</code></em>
 and puts the result in <em class="parameter"><code>timedata</code></em>
.</p>
<p><em class="parameter"><code>freqdata</code></em>
 must have <em class="parameter"><code>len</code></em>
/2 + 1 samples, where <em class="parameter"><code>len</code></em>
 is the parameter specified
while allocating the <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> instance with <a class="link" href="gst-plugins-base-libs-GstFFTF64.html#gst-fft-f64-new" title="gst_fft_f64_new ()"><code class="function">gst_fft_f64_new()</code></a>.</p>
<p><em class="parameter"><code>timedata</code></em>
 must be large enough to hold <em class="parameter"><code>len</code></em>
 time domain samples.</p>
<div class="refsect3">
<a name="gst-fft-f64-inverse-fft.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>self</p></td>
<td class="parameter_description"><p><a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> instance for this call</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>freqdata</p></td>
<td class="parameter_description"><p>Buffer of the samples in the frequency domain</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>timedata</p></td>
<td class="parameter_description"><p>Target buffer for the samples in the time domain</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="gst-fft-f64-window"></a><h3>gst_fft_f64_window ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
gst_fft_f64_window (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> *self</code></em>,
                    <em class="parameter"><code><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> *timedata</code></em>,
                    <em class="parameter"><code><a class="link" href="gst-plugins-base-libs-GstFFT.html#GstFFTWindow" title="enum GstFFTWindow"><span class="type">GstFFTWindow</span></a> window</code></em>);</pre>
<p>This calls the window function <em class="parameter"><code>window</code></em>
 on the <em class="parameter"><code>timedata</code></em>
 sample buffer.</p>
<div class="refsect3">
<a name="gst-fft-f64-window.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>self</p></td>
<td class="parameter_description"><p><a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> instance for this call</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>timedata</p></td>
<td class="parameter_description"><p>Time domain samples</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>window</p></td>
<td class="parameter_description"><p>Window function to apply</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="gst-fft-f64-free"></a><h3>gst_fft_f64_free ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
gst_fft_f64_free (<em class="parameter"><code><a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> *self</code></em>);</pre>
<p>This frees the memory allocated for <em class="parameter"><code>self</code></em>
.</p>
<div class="refsect3">
<a name="gst-fft-f64-free.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>self</p></td>
<td class="parameter_description"><p><a class="link" href="gst-plugins-base-libs-GstFFTF64.html#GstFFTF64" title="GstFFTF64"><span class="type">GstFFTF64</span></a> instance for this call</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
</div>
<div class="refsect1">
<a name="gst-plugins-base-libs-GstFFTF64.other_details"></a><h2>Types and Values</h2>
<div class="refsect2">
<a name="GstFFTF64"></a><h3>GstFFTF64</h3>
<pre class="programlisting">typedef struct _GstFFTF64 GstFFTF64;</pre>
</div>
<hr>
<div class="refsect2">
<a name="GstFFTF64Complex"></a><h3>struct GstFFTF64Complex</h3>
<pre class="programlisting">struct GstFFTF64Complex {
  gdouble r;
  gdouble i;
};
</pre>
<p>Data type for complex numbers composed of
64 bit float.</p>
<div class="refsect3">
<a name="GstFFTF64Complex.members"></a><h4>Members</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="300px" class="struct_members_name">
<col class="struct_members_description">
<col width="200px" class="struct_members_annotations">
</colgroup>
<tbody>
<tr>
<td class="struct_member_name"><p><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> <em class="structfield"><code><a name="GstFFTF64Complex.r"></a>r</code></em>;</p></td>
<td class="struct_member_description"><p>Real part</p></td>
<td class="struct_member_annotations"> </td>
</tr>
<tr>
<td class="struct_member_name"><p><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gdouble"><span class="type">gdouble</span></a> <em class="structfield"><code><a name="GstFFTF64Complex.i"></a>i</code></em>;</p></td>
<td class="struct_member_description"><p>Imaginary part</p></td>
<td class="struct_member_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
</div>
</div>
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